Environmental Potentials whole house surge protection, can I get your opinions?

Soil conductivity (resistance) is relevant for code requirements - that only address human safety. Grounding for appliance safety is why Ufer grounding (to exceed code requirements) is popular. Earthing for protection is an art.

Earth ground for protection involves conductivity and equipotential. For example, a ’whole house’ solution was properly earthed. They still suffered damage. A vein of graphite existed behind the house. Best path to earthborne charges was incoming on AC mains, ignored a service entrance earth ground, passed through household appliances, then out the back of that house into that conductive graphite vein.

Solution surrounded that house with a 2 AWG bare copper ground wire. Then single point earth ground was entirely beneath that house. Best equipotential eliminated future damage. Then a best connection to distant earthborne charges was outside around the house; not through it.

Other considerations. Earth electrode must be over 8 feet deep. If any are loose, then some event (maybe lightning) created that looseness if not enough electrodes were earthed. Always learn from mistakes.  Damage happens because a human made a mistake.  

In one FL case, lightning kept striking an outside wall. So they installed lightning rods. Lightning still struck that wall. Lightning (like other destructive surges) found a best path to earth via plumbing that connected to deeper limestone. Lightning rods were only earthed in sand. Solution was a longer electrode to make contact with that deeper and more conductive limestone. Then lightning stopped striking a bathroom wall.

Protectors are simple science. A ’whole house’ protector must be at least 50,000 amps to survive even direct lightning strikes (ie 20,000 amps). Earth ground (not a protector) does the protection.

Inspect a ground hardwire from the breaker box. If it goes up over the foundation and down to an earthing electrode, then it meets code. (It has low resistance and high impedance.) Surge protection compromised. That hardwire has excessive impedance (ie greater than 10 feet long), has sharp bends, and is not separated from non-grounding wires. Effective protection exists when that hardwire goes through a foundation and down to earth. Then it is shorter. No sharp bends means significantly lower impedance (not resistance). Is routed with more separation from other wires. Then a ’whole house’ protector has better earthing. A protector is only as effective as its earth ground.

Above is a ’secondary’ protection layer. Each layer is only defined by its earth ground - not by any protector. Also inspect your ’primary’ surge protection layer. Pictures (and not text) about half way down after the expression "more safety hazards" demonstrate what to inspect:
http://www.fpl-fraud.com/

Some examples demonstrate this ’art’ of protection. Equipotential and impedance apply. Protection is always about where hundreds of thousand of joules dissipate. A protector is only as effective as its earth ground.

I have yet to hear of a residential electrical contractor that checks for earth resistance.

No standard was defined to measure that resistance. A 25 ohm number is too subjective Rather than play games with local inspectors, electricians routinely earth two ground electrodes. Then nobody can argue about 10 ohms measured one way and 40 ohms measured some other hardware or method.

westom said:
Soil conductivity (resistance) is relevant for code requirements - that only address human safety. Grounding for appliance safety is why Ufer grounding (to exceed code requirements) is popular.

First you need to start with what is the intention of the National Electrical Code.

2014 NEC
Article 90
Introduction

90.1 Purpose.

(A) Practical Safeguarding. The purpose of the National Electrical Code is the practical safeguarding of persons and property from hazards arising from the use of electricity.

"and property".

Then you need to move onto 250.4 (A)(1)

Electrical System Grounding.
Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by, lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.

IEEE

The IEEE Green Book also states that ‘field experience and theoretical studies have shown that arcing, restriking, or vibrating ground faults on ungrounded systems can, under certain conditions, produce surge voltages as high as six times normal. Neutral grounding is effective in reducing transient voltage buildup from such intermittent ground faults by reducing neutral displacement from ground potential and reducing destructive effectiveness of any high-frequency voltage oscillations following each arc initiation or restrike,’

https://www.mikeholt.com/mojonewsarchive/GB-HTML/HTML/NECArticle250Sections250.1-250.4~20020123.htm

Earth grounding for the protection of electronic equipment, Micro processors, Data Processing Centers, Others? What about the electrical equipment and appliances found in the home? What doesn’t have a Micro Processor in it today, or at least electronics?

Again, the IEEE Green/Emerald book recommends a ground resistance of 5 ohms or less.

I believe so does the NFPA.
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westom                                      22 posts               12-27-2016 12:48pm

I have yet to hear of a residential electrical contractor that checks for earth resistance.

No standard was defined to measure that resistance. A 25 ohm number is too subjective Rather than play games with local inspectors, electricians routinely earth two ground electrodes. Then nobody can argue about 10 ohms measured one way and 40 ohms measured some other hardware or method.

First my comment is part of the total response I gave to the question gdnrbob asked in a post.

Quote

gdnrbob said:
So, it seems the ground may be a place I should be inspecting more closely. As my house is almost 100 years old, is there any way to test a ground? Or, is there any way to add a newer/more effective ground?
Thanks Bob

Does gdnrbob’s 100 year old house have a Concrete Encased Electrode (Ufer ground)? No.....

So what does gdnrbob possibly have for a Grounding Electrode System?
First it would help to know when, the year, the electrical service was last updated.
IF the house has a steel or copper domestic water line that is, at least 10ft in length, buried horizontally in the earth, that is a grounding electrode as per NEC. IF that is the case there is a very high probability it is supplemented by at least one 8ft ground rod. IF the water line is plastic then more than likely he has two 8ft ground rods, minimum, making up his grounding electrode system for the electrical service. The above would satisfy older NEC bare minimum requirements.
As always the AHJ has the final say.

westom said:
No standard was defined to measure that resistance.

Are you saying there is not a recognized, accepted, electrical industry standard for testing soil resistivity? I thought ANSI/IEEE recognized the testing equipment when used as directed by the manufacture, of the test equipment. Yes, the equipment test, to be credible, must be preformed by a qualified person trained on its’ use.

weston said:
Rather than play games with local inspectors, electricians routinely earth two ground electrodes.

Games? Which is cheaper for the Residential Electrical Contractor? Pay a certified Power Quality company to test the electrode soil resistance and produce a certified test report for the electrical inspector, and possibly the Utility Power Company’s inspector, or just drive an additional 5/8" X 8ft ground rod?

//

In the 1968 NEC edition the "Concrete Encased Electrode" (Ufer ground) was first written into the code. AHJs (Authority Having Jurisdiction) could have made it mandatory if they wanted to. Maybe some did.

In NEC 2005 the language, wording, was changed making it mandatory for new construction.
Of course that doesn’t mean all States and or local AHJs adopted the 2005 NEC change. My State did but not my city’s AHJ. Just going from memory I think the AHJ adopted the mandatory change around the year of 2009. Probably was when the AHJ adopted the NEC 2008 code in January of 2009,(In part with deletions and amendments). I don’t remember for sure..... I do know in 2007 it was not mandatory in my city.
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NFPA is a human protection code; insufficient for transistor protection. Transistor protection both *meets* and *exceeds* those human safety requirements.

Human safety discusses resistance. Transistor safety also addresses impedance and equipotential. NFPA does not discuss the latter two. Because NFPA is only about human protection.

First you need to start with what is the intention of the National Electrical Code.

I did. Stated repeatedly in multiple posts. Appliances protection both *meets* and *exceeds* what is required by human protection codes such as NFPA.

IEEE defines how to exceed those codes. IEEE say why ’whole house’ protection is 99.5% to 99.9% effective. Plug-in protectors have no earth ground - maybe add another 0.2% protection. None of that contradicts what is good earthing for human protection and remains insufficient for appliance protection.

More quotes from various IEEE sources:

It is important to ensure that low-impedance grounding and bonding connections exist among the telephone and data equipment, the ac power system’s electrical safety-grounding system, and the building grounding electrode system. ..Failure to observe any part of this grounding requirement may result in hazardous potential being developed between the telephone (data) equipment and other grounded items that personnel may be near or might simultaneously contact.

Low impedance - not low resistance.

Martzloff’s 1994 IEEE paper says same about impedance because a protector (SPD) is only as effective as its earth ground:

An effective, low-impedance ground path is critical for the successful operation of an SPD. ... Therefore, an evaluation of the service entrance grounding system at the time of the SPD installation is very important.

An IEEE guide shows a protector, connected to a wall receptacle safety ground, earthing an 8000 volt surge destructively through a nearby TV. That protector was not connected low impedance to earth ground; was too close to and therefore damaged a nearby appliance. Again, protection defined by impedance - a short connection to earth. Protection not provided by a wall receptacle safety ground - that has low resistance and high impedance.

That same guide defines earthing that must exceed NFPA requirements:

To achieve optimum overvoltage protection, the connecting leads between the SPDs and the panel or protected equipment should be as short as possible and without sharp 90-degree bends.

90 degree bends and long wires (ie more than 10 feet) increase impedance (but not resistance). Therefore reduce appliance protection. NEC defines human protection; not appliance protection. Unfortunately electricians, who are taught code, are not taught concepts such as counterpoise, equipotential, and impedance. Concept necessary to upgrade earthing for surge protection.

Low impedance connection to single point earth ground is why the Cutler-Hammer and Leviton ’whole house’ protectors are so effective. With numbers (ie 50,000 amps) that define protection from direct lightning strikes. Because a protector is only as effective as its earth ground - including a low impedance connection.

Also critical is inspecting the ’primary’ surge protection layer - that is ignored by NFPA and NEC.